Here are some Pit Bull friendly resources, including companies that do not discriminate against the breed.
*NOTE* this page is under construction. Please check back for updated info soon!
State Farm Insurance prides itself on being Pit Bull and Bully breed-friendly. They stand by the phrase "it's not the breed, it's the bite". Therefore, they're definitely the go-to when it comes to zero discrimination.
Nationwide Insurance will cover you if you have a Pit, however they require a Canine Good Citizen Certification from the American Kennel Club. They want to make sure your dog is "well-behaved" and can pass some basic tests (ie: sitting, not barking at strangers, etc.).
Allstate Insurance does not discriminate against Bully breeds and instead asks that all owners be responsible regardless of the breed to minimize risks.
USAA will cover your Pit Bull, no problem. However take note that the insurance company is only for active military, veterans, and family of armed service members.